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Home >> Chevrolet >> 2024 >> Tahoe Commercial, 4WD >> Repair and Diagnosis >> Accessories & Equipment >> Interior/Exterior Trim >> Bumpers And Fascias >> Diagnostic Information and Procedures >> Active Grille Air Shutter 2 Malfunction >> Circuit/System Testing

Circuit/System Testing

    NOTE:

    It may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

  1. Ignition/Vehicle & All vehicle systems - Off
  2. Disconnect the electrical connector: M60A Active Grille Air Shutter 1 Motor Module/M96A Active Grille Air Shutter 1 Actuator.
  3. Disconnect the electrical connector: M60B Active Grille Air Shutter 2 Motor Module/M96B Active Grille Air Shutter 2 Actuator.
  4. Test for less than 10 ohms between the test points: Ground circuit terminal@M60B Active Grille Air Shutter 2 Motor Module/M96B Active Grille Air Shutter 2 Actuator & Ground
    • If 10 ohms or greater 
    1. Disconnect the ground connection: Ground circuit terminal
    2. Test for less than 2 ohms between the test points: Ground circuit terminal@Component harness & Ground circuit terminal
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Repair the open/high resistance in the ground connection.
    • Go to next step: If less than 10 ohms 
  5. Ignition - On/Vehicle - In Service Mode
  6. Verify a test lamp turns On between the test points: Ignition circuit@Component harness & Ground
    • If the test lamp does not turn On and the circuit fuse is OK 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for less than 2 ohms between the test points: Ignition circuit@Component harness & Output terminal@M96 Fuse
      • If 2 ohms or greater - Repair the open/high resistance in the circuit.
      • If less than 2 ohms - Verify the fuse is OK and there is voltage at the fuse.

        Or

      • If less than 2 ohms - Refer to: Power Mode Mismatch
    • If the test lamp does not turn On and the circuit fuse is open 
    1. Ignition/Vehicle - Off & Remove - Test lamp
    2. Test for infinite resistance between the test points: Ignition circuit@Component harness & Ground
      • If less than infinite resistance - Repair the short to ground on the circuit.
      • If infinite resistance - Replace the component: M60B Active Grille Air Shutter 2 Motor Module/M96B Active Grille Air Shutter 2 Actuator.
    • Go to next step: If the test lamp turns On 
  7. Ignition/Vehicle OFF, disconnect all LIN devices that share the same LIN serial data circuit.
  8. Ignition ON/Vehicle In Service Mode.
    9. NOTE:

    For accurate voltage reading, disconnect the battery charger prior to performing the following test step.

  9. Test for 3.5-12 V between the LIN serial data circuit terminal and ground.
    • If less than 3.5 V 
    1. Ignition/Vehicle OFF, disconnect the harness connectors at the K20 Engine Control Module.
    2. Test for infinite resistance between the LIN serial data circuit terminal and ground.
      • If less than infinite resistance, repair the short to ground in the circuit.
      • Go to next step: If infinite resistance
    3. Test for less than 2 Ω in the LIN serial data circuit end to end.
      • If 2 Ω or greater, repair the open/high resistance in the circuit.
      • Go to next step: If less than 2 Ω
    4. Replace the K20 Engine Control Module.
    • If greater than 12 V 
    1. Ignition/Vehicle OFF, disconnect the harness connectors at the K20 Engine Control Module.
    2. Ignition ON/Vehicle In Service Mode.
    3. Test for less than 1 V between the LIN serial data circuit terminal and ground.
      • If 1 V or greater, repair the short to voltage in the circuit.
      • Go to next step: If less than 1 V
    4. Replace the K20 Engine Control Module.
    • Go to next step: If between 3.5-12 V 
  10. Verify how many LIN devices are connected to this LIN circuit.
    • If there is only one LIN device 
    1. Ignition/Vehicle OFF, inspect both harness and component connectors for contamination, corrosion, and terminal tension.
    2. Reconnect the harness connectors at the LIN device. Verify all connectors/terminals are fully seated.
    3. Ignition ON/Vehicle In Service Mode.
    4. Verify the DTC is not set again.
      • If the DTC is set, replace the LIN device that is not communicating.
      • Go to next step: If the DTC is not set
    5. A fault is currently not present and may be an intermittent condition.
    • Go to next step: If there are two or more LIN devices 
  11. Ignition/Vehicle OFF, disconnect the harness connectors at the K20 Engine Control Module.
  12. Reconnect the harness connectors at the first LIN device.
  13. Ignition ON/Vehicle In Service Mode.
  14. Test for 3.5-12 V between the LIN serial data circuit terminal at the K20 Engine Control Module and ground.
    • If less than 3.5 V or greater than 12 V 

      Replace the LIN device that was just connected.

    • Go to next step: If between 3.5-12 V 
  15. Ignition/Vehicle OFF, reconnect the harness connectors at another LIN device.
  16. Ignition ON/Vehicle In Service Mode.
  17. Test for 3.5-12 V between the LIN serial data circuit terminal at the K20 Engine Control Module and ground.
    • If less than 3.5 V or greater than 12 V 

      Replace the LIN device that was just connected.

    • Go to next step: If between 3.5-12 V 
  18. Repeat steps 15-17 for the remaining LIN devices until a faulty LIN device is identified. If there is no faulty LIN device, replace the M60B Active Grille Air Shutter 2 Motor Module/M96B Active Grille Air Shutter 2 Actuator.
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